Control of Litter
As sanitary landfills continue to grow higher in elevation, and as surrounding areas continue to be developed, landfill operators are facing increasing problems with blowing litter. Blowing litter causes complaints from neighbors, citations from regulatory agencies, and labor cost to clean it up. Landfill operators use operational precautions, such as coordinating waste receipts and waste placement with wind conditions, to control blowing litter. However, extreme winds, or any winds during a lapse in these precautions, can cause litter transport far beyond landfill boundaries. Landfill operators also use stationary fencing around the perimeter of a landfill site to control blowing litter. However this fencing is only partially effective. The fencing is stationary and cannot be moved to adjust to changing site and wind conditions. It is also often far away from the active waste face, the source of the litter. Litter often blows upward and outward from the active face, high above and over stationary fencing.
Landfill operators also fabricate large mobile barriers on-site, in a variety of forms and dimensions, to reduce blowing litter. These devices consist of a steel skid or truck and framework to position and support a large area of open screen material downwind of the active waste face. The screen material is typically chain-link fencing, welded wire, expanded steel, or plastic construction fencing. The screen lets wind pass through, but stops litter. There are a variety of methods to move these mobile barriers to adjust to changing site and wind conditions. Some mobile barriers are mounted on skids, while others are mounted on a passive truck with wheels and tires. These mobile barriers can be pulled or pushed over the ground. Yet other barriers have a lifting bale that provides for picking up and moving the barrier with the blade of a bullzoder or landfill compactor (hereinafter “machine”). These mobile barriers can prevent litter from blowing beyond landfill boundaries. However they have several common deficiencies that impair their performance and utility:
They are not as mobile as they need to be. They lack provisions for readily moving them to the most appropriate location to adjust to changing site and wind conditions, in time to be effective. Barriers on skids or trucks are difficult and time-consuming to pull or push across unstable ground without sticking or damage. Tires become punctured and flattened when rolled over refuse. Pulling these barriers requires the machine operator to dismount the machine to hook up to the barrier. This is undesirable in areas of treacherous ground or during inclement weather. Lifting bales are not adjustable and can only accommodate one particular machine. Also, the bales are usually on the downwind side of the barrier, requiring the machine to traverse around the barrier to pick it up. Because of these difficulties the barriers typically stay in one place even as the waste face constantly moves throughout the life of the landfill and as wind conditions change. Therefore they are seldom positioned in the most appropriate location to effectively control litter.
They are not suitable for positioning close to, or within, the active waste face that is the source of the litter. They sink into unstable refuse or ground, get stuck, or tip over. They are difficult to remove or right without damage. Consequently they are positioned at some distance from the active face, in more stable ground. This substantially increases the perimeter along which they are to intercept blowing litter, thereby requiring more barriers than if they could be positioned closer to the active face. As blowing litter rises outward and upward from the active face, it is more likely to blow high above and over these mobile barriers.
Their screens have catches, pinch points, and obstructions that tend to trap litter against the screen, even after the wind has subsided. This “blinding” is unsightly, reduces effectiveness of the barriers, and increases wind loads, making the barriers prone to tipping.
Plastic construction fencing is prone to wind buffeting and resulting premature failure.
Their designs do not consider the full loading of high winds and they are therefore prone to tipping.
They are difficult to position end-to-end with the result of allowing gaps in coverage. Consequently litter blows through, between the ends of multiple barriers.
They are not matched in scale to the heavy machinery with which they are used. They are often frail structures in comparison to these machines, difficult to see and easy to damage.
They have no provisions for convenient disassembly and reassembly that would be necessary, because of their large size, to ship them to or from landfill sites. By “convenient” I mean that disassembly and reassembly would require no cutting or welding of steel. Consequently they must be custom-fabricated on-site, generally under inadequate conditions to produce effective barriers at reasonable cost. Therefore the barriers do not lend themselves to economies of standardization, interchangeable parts, mass production, and shipping efficiency.
Known mobile barriers can control blowing litter. However, the aforementioned deficiencies impair their performance and utility to the point where they are not very effective. Ineffective litter control is a liability to the landfill operator in the form of neighbor complaints, regulatory citations, and clean-up costs. Therefore there is a need for an improved mobile barrier to control blowing litter.
Control of Wind
As public awareness of air quality continues to increase, and as governments respond with stricter laws and regulations, suspension and transport of airborne contaminants is an increasing problem for earthwork, landfill, and surface mining operations. The airborne contaminants are typically gasses, vapors, dust, and litter. Controlling wind across the active face of these operations can reduce suspension and transport of these contaminants.
Wind barriers can control wind speed across the active face of earthwork, landfill, and surface mining operations, thereby reducing suspension and transport of airborne contaminants. Wind barriers are also known in the fields of agriculture, erosion control, and snow control. In these applications, they protect sensitive crops from wind damage, protect sensitive soils from wind erosion, and prevent snow drifting over roads.
Known wind barriers consist of stationary fencing of wind-reducing lath or fabric. The lath or fabric has an “aerodynamic opacity” that lets some wind through, thereby reducing wind speed without causing turbulence. They are installed upwind of an active face. These barriers can reduce suspension and transport of airborne contaminants beyond site boundaries. However they have some deficiencies that impair their performance and utility:
Because of their aerodynamic opacity they are prone to high wind loads, often resulting in damage, tipping, and failure.
The wind-reducing fabric is prone to wind buffeting and resulting premature failure.
They are not suitable for positioning close to, or within, the active face that is the source of the airborne contaminants. This substantially increases the perimeter along which they are to control wind, thereby requiring more barriers than if they could be positioned closer to the face.
They are not mobile and therefore cannot adjust to changing site and wind conditions.
Although they reduce suspension and transport of airborne contaminants, such suspension and transport remains a significant problem.
Known wind barriers can control wind, thereby reducing suspension of airborne contaminants from earthwork, landfill, and surface mining operations. However, the aforementioned deficiencies, particularly their lack of mobility, impair their performance and utility to the point where they are not very effective. Ineffective control of airborne contaminants is a liability to these operations in the form of neighbor complaints and regulatory citations. Therefore there is a need for an improved mobile barrier to control wind and to reduce and control airborne contaminants.
Misting Systems
Misting systems are a known means to control suspension and transport of airborne contaminants from earthwork, landfill, and surface mining operations. They work in two ways: wetting and cooling. Misting systems control dust by wetting dust particles with water mist, thereby adding weight to the particles and providing adhesion between particles. In this case the misting system produces fluid droplets which are relatively large. In cooling applications, misting systems control volatilization of gasses and vapors by evaporative cooling thereby reducing volatilization rates of the source. Misting systems may also be used to dispense odor suppressants into the air, thereby reducing offensive odors from landfills and the like. Misting systems have also been used to dispense bird repellents to control the feeding of seagulls and other avian species at landfills. In the cases of odor and bird control and evaporative cooling, the misting system produces fluid droplets which are very small.
There are several disadvantages to known misting systems. The most important disadvantage occurs when misting systems are used in open air operations. Frequently mist applied in open air operations is blown away by wind before it has beneficial effect, and it is difficult to retain the mist where it is needed. There are also problems with autonomy and mobility of known misting systems. Known systems usually rely on external power and water and are not suited to moving around a landfill, for example, on a daily basis. Lastly, most commercially available systems lack convenient operational control and are prone to excessive water consumption and accumulation on the ground.